In view of the environments in which they are used which are in some cases very hard to control, many force-measuring devices, in particular gravimetric measuring instruments such as for example balances used in particular in the laboratory or in production facilities, or retail store scales, thermogravimetric instruments, measuring instruments for the gravimetric determination of moisture content, weighing modules for storage tank installations and reactor vessels, weighing modules and installations of multiple weighing modules in filling- and packaging lines, and—likewise—torque-measuring devices and accelerometers are protected by effective measures against non-ionizing types of radiation, in particular electromagnetic fields. These protective measures include among other things that the force measuring devices are adapted to the environments in which they are used in conformance with specific regulatory requirements in regard to radiation resistance and the like, as stated for different classes of exposure in the norm standards EN45501 or IEC61326.
For example, force-measuring cells for weighing modules are installed in metallic enclosures made of steel. The force-measuring cells enclosed in housings of this kind work problem-free as long as the housing keeps the radiation effects which compromise the measuring signal sufficiently away from the force-measuring cell and the measuring electronics or, in other words, prevents high-frequency electromagnetic fields from penetrating into the interior of the housing.
However, in situations where the gravimetric measuring instruments, weighing modules or balances are exposed to exceptionally high field strengths, it could still happen in some cases that certain high-frequency electromagnetic fields could penetrate through the smallest openings and gaps into the interior of the housing and compromise the measurement accuracy of the weighing modules to a noticeable degree.
The errors caused in the measurement results could lead to inaccurate weighing processes. If the measuring device is incorporated in an industrial installation with a high degree of automation, a disturbance of the measuring device could even lead to defective products.
In the case of a retail store scale that is used for the selling of merchandise, a customer could be charged a price that is either too low or too high if a product is weighed with an inaccurate or completely wrong weighing result.
It could happen that as a result of a manipulation error and/or inattention with telecommunications equipment, high-frequency electromagnetic fields penetrate into the interior of the housing and increase the radiation density in the interior space of the housing to such a degree that parts of the force-measuring cell or the components of the signal-processing portion or of the measurement electronics portion are compromised in their measuring accuracy. The term “telecommunications equipment” in this context encompasses a multitude of possible devices that are based on the principle of electromagnetic radio transmission, such as mobile telephones, cordless telephones, radio communications equipment, wireless data transmission, RFID devices, etc.
It is further conceivable that someone might want to change the measurement result of a force-measuring device through intentional manipulation by means of high-frequency radiation.
It is therefore an objective to propose an improved method for monitoring and/or determining the condition of a force-measuring device, and to also propose a force-measuring device capable of operating under the improved method.